Collaborative Study of Ice-Ocean Interaction in Svalbard

将在自然环境中研究海冰形成的小尺度物理，目的是解决关于冰形成速度、海洋边界层中的过冷以及热和盐的有效扩散系数的关键悖论。影响海冰质量和能量平衡的因素目前引起了人们的极大兴趣，这既是因为海冰对气候变化的潜在影响，也是因为越来越多的证据表明北极正在发生快速变化。这个问题的一个重要方面是冰-海界面上的热量和盐分交换。在这一点上，理论和观察之间存在着巨大的差距。目前的理论认为，增长冰下的边界层应受到冰-海界面的双重扩散过程的约束，以迫使边界层过冷和原位形成脆性冰。理论还表明，薄冰下的海洋热通量将大于厚冰下的海洋热通量。这些结果极大地影响了小尺度和超大尺度的模型。然而，观察表明，这些事情并没有发生。这可能是因为现有的边界层理论不能很好地代表冰形成过程的微观物理。这项工作将与挪威的同事合作，进行一项观察和理论相结合的调查，以检验这些假设。观测工作将在斯瓦尔巴特群岛冰冻但潮汐活跃的峡湾中的快速冰中进行。通过适当的规划和准备，以及从现有的广泛后勤基地进行操作的能力，峡湾环境将为研究小规模冰与海洋的相互作用提供一流的天然实验室。这项工作将利用NSF-OPP和诺斯克极地研究所最近签署的合作声明(SOC)，它体现了美国和挪威科学家之间的密切互动。我们将通过以下方式使教育外展成为该项目的重要组成部分：支持一名将参加大学斯瓦尔巴群岛课程的美国研究生，与大学学生在实地合作，并在大学大学讲课。

The small-scale physics of sea ice formation will be studied in a natural setting with the objective to resolve critical paradoxes about the rate of ice formation, supercooling in the ocean boundary layer, and the effective diffusivities of heat and salt. Factors affecting the mass and energy balance of sea ice are currently of much interest both because of the potential impact of sea ice on climate change, and because there is a growing body of evidence that rapid changes are occurring in the Arctic. An important facet of the problem is the exchange of heat and salt at the ice-ocean interface. Here there is a significant gap between theory and observation. Current theory suggests the boundary layer under growing ice should be constrained by double diffusive processes at the ice-ocean interface to force supercooling and in situ frazil ice formation in the boundary layer. Theory also suggests that ocean heat flux will be greater under thin ice than thick ice. These results greatly affect models for small scales and very large scales. Yet, observations indicate these things do not happen. This may be because the existing boundary layer theories do not properly represent the microphysics of the ice formation process. This effort will cooperate with Norwegian colleagues in a combined observational and theoretical investigation to test the hypotheses. The observational work will be done from fast ice in frozen but tidally active fjords in Svalbard. With proper planning and preparation, and the ability to operate from an extensive existing logistics base, the fjord setting will offer a superb natural laboratory for investigating small-scale ice-ocean interaction. This work will take advantage of the recently signed Statement of Cooperation (SOC) between NSF-OPP and the Norsk Polar Institute, and it exemplifies close interaction between U.S. and Norwegian scientists. We will make educational outreach an important part of this project by: supporting a U.S. graduate student who will attend University Courses on Svalbard (UNIS), working with the UNIS students in the field, and giving lectures at UNIS.